Do you know the dirty dozen fruits and vegetables and how to recognize them?

The "dirty dozen" are the crops containing the most pesticides when grown using conventional, non-organic methods. Compared to similar organically grown produce, they contain hundreds of pesticides and other chemical treatments, many of which can put consumers at risk of a variety of health problems and diseases.

The Environmental Working Group, a nonprofit watchdog effort devoted to monitoring corporate use of natural resources, compiled the list using over 43,000 studies and tests conducted by the FDA and USDA between 2000 and 2004. Forecasts compiled by the EDW showed that consumers could cut their pesticide intake as much as 90 percent by buying only organically grown fruits and vegetables on the list.

For EDW officials, the proof is positive as to the dangers of commercial produce. "Federal produce tests tell us that some fruits and vegetables are so likely to be contaminated with pesticides that you should always buy them organic," said Richard Wiles, EWG's senior vice president. "Others are so consistently clean that you can eat them with less concern."

Eating the dirty dozen together exposes the consumer to as many as 15 pesticides at one time. Among the dirty dozen itself, peaches and apples topped the list, with almost 97 percent of peaches testing positive for pesticides and 87 percent testing positive for two or more pesticide residues. 92 percent of apples tested positive, with 79 percent showing a positive result for two or more. Other fruits and vegetables on the list included sweet bell peppers, celery, nectarines, strawberries, cherries, pears, imported grapes, spinach, lettuce, and potatoes.

The EDW also released a Consistently Clean list, including the 12 fruits and vegetables least contaminated by pesticide treatment. Topping this list were onions, avocados, and sweet corn. In each case, over 90 percent of samples tested had little or no pesticide residue. Pineapples, mango, asparagus, sweet peas, kiwi, bananas, cabbage, broccoli, and papaya rounded out the list.

The list of fruits and vegetables is particularly alarming given that recent government studies show that washing fruits and vegetables in tap water is no longer a sure way to remove all pesticides and chemicals. Peeling also reduces exposure, though some nutrients are lost when the peel is discarded.

The USDA heavily regulates pesticide use, though enforcement has often proven difficult. Meanwhile, the related health concerns are becoming more apparent. Studies show early exposure to pesticides has been linked to leukemia, brain cancer, and birth defects in children. A 2006 study by the United States National Research Council found that pesticide intake among school children dropped dramatically and immediately when their dietary fruits and vegetables were switched to those grown using organic methods.

Finally, the EDW has created a free, wallet-sized card outlining the Dirty Dozen and Consistently Clean produce lists that can be ordered for free at http://www.foodnews.org/. The guide is available in English and Spanish language versions.